[front-loading this caveat: I'm speaking from the POV of a web developer]
It's hard not to agree with the general premise of the article - anyone can see the trend. But as always, there's some nuance that I think the article leaves out.
Thinking of it as "two different types of programmers" is reductive and encourages you to have a fixed mindset about people (i.e. I "am" a packer vs I "am" a mapper). Really, these are two sets of behaviors and approaches towards software engineering, and almost everyone has bits of both behaviors.
I began my tech career in web development in 2009, before all the frameworks and bootcamps and influencers. In those days there was still a massive focus on performance, and since bundlers weren't really a thing yet, a lot of the stuff was made in-house. I obsessed over fine-tuning the critical rendering paths of my websites, even hand-modifying SVGs so I could strip out unnecessary vector points. I went a little overboard at times.
I didn't use a JS framework (other than jQuery) until 2016, and since then, I have to admit that my mapper brain has atrophied into a packer brain. In my opinion, my industry has undergone two significant changes:
1. We've been under increasing pressure to ship as fast as possible, which encourages a packer mentality.
2. We've seen an explosion of VC-backed technologies that are impossible to keep up with.
Both of these things together make it very difficult to resist packer-behavior. For instance, when I first read about NextJS and the idea of "hydration", I felt this overwhelming sense of weariness. I could immediately imagine what they were doing at a high level, because I understand the fundamentals of web technology. But still, I also knew that in order to use NextJS effectively, I'd have to spend hours digging through their documentation to learn the nuances of their approach. At my age, I simply don't have the time or energy, especially if they're going to ditch that approach in their next version.